As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT/RT RECIRCULATION FANS SO LOUD THAT CHECKLIST RESPONSES AND COCKPIT COMMUNICATIONS ARE HARD TO HEAR. WHENEVER CREW USES HAND MICROPHONE IN FLIGHT, ATC HAS DIFFICULTY UNDERSTANDING COMMUNICATION BECAUSE OF BACKGROUND AIR NOISE. CLEANED DISTRIBUTION DUCTS FROM STEM TO STERN INCLUDING SIDEWALL DIST HOSES AND DIFFUSERS. AIRFLOW HAS BEEN GREATLY IMPROVED.